Charge forming device



Feb. 9, 1932. w.,H. TEE-mn 1,844,723

CHARGE FORMNG- DEVICE Filed DSG. 28, 1928 Patented Feb. 9, 1932 UNITED srares P''T OFFICE WILFORD H. TEETER, OF DAYTON, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO DELCO PRODUCTS CORPORATION, OF DAYTON, OHIO, A CORPORATION OF DELL-AWARE CHARGE romaine DEVICE Application led December 28, 1928.

This invent-ion relates to charge forming devices for internal combustion engines and more particularly to the type of charge forming device Which comprises a plurality of priadapted to deliver a primary mixture of air and fuel to one of a plurality of secondary mixing chambers, one of Which is associated with each engine intake port andeach of which receives air When required through one of the branches of an air manifold having a single air inlet. A common fuel reservoir supplies liquid fuel to all of said i primary carburetors.

Examples of charge forming devices of this character are disclosed in the cepending applications of Wilford H. Teeter, Se rial No. 221,372,1iled September 22,1927, and Fred E. Aseltine and Wilford H. Toeter, Serial No. 221,371, filed September 22, 1927.

In devices of this character such as heretofore constructed, as for instancethose disclosed in the above applications, certain difficulties have been encountered in the provision of means to supply yfuel for idling` and acceleration, to supply a mixture ofproper proportions for other engine operation, and to secure equal distribution of the fuel for idling and acceleration to the various engine intake ports.

It is, therefore, the principal obj ect of the present invention to provide improved means for supplying the desired quantity of fuel for any idling operation and means operative on acceleration for enriching the mixture normally supplied to the desired extent, and further to secure proper distribution of this fuel for idling and acceleration, to the various engine` intake ports.

It is a further object of theinvention to supply the idling mixture and the additional fuel supplied for acceleration through a com* mon fuel supply passage, so as to simplify the construction and reduce the cost and difficulty of manufacturing.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to 53 the accompanying dravvingsvvherein a premary mixing chambers, each of which is Serial No. 328,904.

ferred embodiment of one form of the present invention is clearly shown.

ln the drawings: v

Fig. 1 is a longitudinal vertical section through the carburetor unit and middle outlet branch of the manifold.

Fig. 2 is a transverse section on line 2-2 of Fig. 1.

Figs. 3, 4, and 5 are fragmentary sections on the lines 3-3, 4 4, and 5 5, respectively,

of Fig. 1.

The drawings disclose a charge forming device comprising a main air manifold 10, having three outlet branches, the middle branch 12 being shown herein. Each of these branches communicates with one of the intake ports 14 of a multicylinder engine and each is provided with an attaching flange 16 for securing the manifold tothe engine block in the usual manner. `Adjacent the inlet of the manifold is provided a flange 18 to Which the main carburetor unit is adapted to be attached, as shown in Fig. 1.

The carburetor unit comprises a main housing 20, having an attaching flange 22, adapted to be secured to the flange 18, by screvvs 24. An air inlet horn 28 is secured in position to register With an opening in the upper Wall of the housing 20 in any suitable Way. A casting 30, having certain dash pot chambers and fuel passages formed therein, as will be fully described later, is secured in any suitable Way to the bottom Wall of the housing 20, as shown in Fig. 1, and a sheet metal fuel bowl 32 isheld tight against an annular shoulder 34, by a screw or any other suitable means. Fuel is conducted from a main source of supply to the fuel bowl through a conduit not shown herein, and the flow of fuel to the bowl is controlled by a float 36, operating in the usual manner to maintain a substantially constant level of fuel therein.

Fuel flows from the bovvl 32 to a plurality of primary fuel nozzles 38, one of which is located in each of the primary mixture pas sages 40, the construction of Which is briefly described hereinafter. The fuel conduit be tweenthe fuel bowl and the nozzles comprises a vertical fuel passage 42, communicating at its upper end Witha horizontal fuel canal 44, which connects with each of the fuel nozzles through orices 46. Fuel is admitted from the fuel bowl to passage 42 at all speeds through al fixed metering orifice 48, and at high speeds additional fuel is admitted through an orifice controlled by a valve 52 in the manner set fort-h in the above applications.

Fuel is lifted from the fuel bowl through the above described fuel passages and nozzles to the mixture passages by the suction maintained therein. Closing movements of the throttle cause al reduction in suction in the mixture passages which might permit the fuel column to drop sufficiently to cause a temporary fuel starving of the engine. To prevent such an occurrence a check valve is provided in an enlarged chamber 56 at the junction of channels 42 and 44, and on reduction of suction in the mixing chamber is adapted to seat on an annular bead 57 formed on the bottom of chamber 56, thus preventing any downward flow of fuel.

Each primary fuel nozzle is provided with an open upper end forming a main fuel outlet, and a secondary fuel outlet comprising two orifices 60 and 62 in the side of the nozzle near the bottom of the mixture passage. At relatively high speeds the suction in the mixture passage is enough to draw fuel from the main outlet as well as from the orifices 60 and 62. At idle or low speeds, however, the suction is sufficient to lift fuel only to some point between the top of the nozzle and orifices 60 and 62, fuel flowing through these orifices by action of gravity. Each nozzle is provided with a restricted fuel metering orifice 68. The primary mixture passages 40 are parallel to each other and close together, as indicated in Figs. 2 and 3, and when the carburetor is attached to the manifold, these passages register with conduits which convey the primary mixture to the secondary mixing chambers, as fully disclosed in the prior applications above referred to.

A single throttle valve G4, which extends across all the primary mixture passages, controls the flow therethrough and is provided with grooves 66 which register with said mixture passages. This throttle is operated by means fully disclosed in the above applications and which forms no part of this invention. The middle primary mixture passage registers with a tube 68, secured in the manifold outlet branch 12, and which conveys the primary mixture to the secondary mixing chamber in that specific branch of the manifold.

Nearly all the air entering the carburetor flows through the air horn 28, controlled by a main air valve 70, normally held against aseat 72 by a spring 74, received between the valve and a iiange 76, projecting from a sleeve 78, slidably mounted on a stationary guide sleeve 80, fixed in the housing 20, and serving as a guide for the stem 82, to which the air valve is secured. l

Vlhen it is desired to choke the carburetor to start the engine, the flange 7 G is adapted to be lifted by an arm 83 until the upper end of the sleeve 78 engages the valve to hold it against its seat, as fully described in the above applications. Suiicient air to carry the starting fuel from the nozzles to the intake ports is admitted through orifices 84 in the main housing 20, as shown in Fig. l.

The valve admits air to a main air chamber 88, from which air flows to the primary mixture passages through an orifice in the floor of the air chamber Aand to the secondary mixing chambers through a passage 92, which connects with the inlet of the manifold l0. A manually operable throttle operated concurrently with the primary throttle by means which forms no part of this invention, but is fully shown in the above mentioned applications, controls the flow through the passage 92.

On any increase of suction in the air chamber 88, the air valve is opened against the pressure of its closing spring to admit additional air and increase the quantity of mixture supplied to the engine. The opening of the valve must be retarded to some extent, however, to prevent fluttering of the air valve and temporary leaning of the mixture. To accomplish this result a dash pot is provided which comprises a cylinder formed in the casting 80, and a piston 102, slidable within the cylinder and secured to the lower end of the air valve stem 82 by any desirable means such as a nut 104. In addition to retarding the opening of the air valve, this dash pot is constructed to pump fuel into the mixture passages 40 on opening movements of the throttle, to enrich the mixture during the acceleration period, as will be fully described l ereinafter.

.ln devices of the type shown herein, such as heretofore constructed, fuel for idling is supplied by the same nozzle which supplies fuel for other engine operation. This nozzle is situated anterior to the primary throttle and said throttle is designed to remain slightly open during idling` operation to permit the idling mixture to flow to the intake ports. lVith this construction it is difficult to form a mixture of proper proportions during all operating conditions. If for instance, the fuel inlets are calibrated to supply a rich enough mixture at idling, at certain other speeds the mixture will become too rich, resulting in faulty engine operation. According to the present invention, t-he idling mixture is supplied to the mixture passages 40 through separate fuel inlets which comunicate with he said mixture passages between the primary throttle valve and the intake ports; the throttle is held almost completely closed during idling and air for carrying the idling Cil fuel is supplied primarily through said fuel inlets, which supply an emulsion or rich 1nixture of fuel and air.

As shown in the drawings, this idling dcvice comprises an additional fuel supply pas- 'is adapted tol admit fuel tothe passage 110 under certain operating conditions. The pas`- sage connects at its upper end with a horizontal passage which extends transversely of the main carburetor unit and is bored in the casting 30.` Orifices 122 are provided to connect the passage 120 with a plurality of calibrated fuel metering plugs 124, screwed into the bottom wall of the main housing and communicating with a plurality of horizontal passages 126 bored in the wall of the main housing longitudinally of the main carburetor unit andsubstantiallyparallel to the mixture passages 40. Restricted vertical fuel inlet passages 128 are provided to connect the posterior ends of the passages 126 with mixture passages at a point immediately posterior to theprimary throttle. The passages 126 at their anterior ends communicate with a horizontal passage 130, which con# nects with an angular air inlet passage communicating with the upper part of the float chamber and, controlled by a valve 134,

adjustable in the housing 20, as indicated in Fig. 1, and adapted tocontrol the admission of air to the passages 126, and thus regulate the proportions of fuel and air in the mixture` supplied during idling operation through the fuel inlets 128. lVhen the primary throttle is closed, the suction effective on the fuel inlet passages 128 enough, if the valve v13/1- properly adjusted, to lift fuel from the various fuel passages above described, to the passages'126, the flow of fuel being` regulated by the metering plugs 124. Air is admitted through passages 130 and 132 in such quantity as determined by the valve 13d, and forms an emulsion with the fuel in passages 126, which is drawn into the mixture passages 40 through the inlets 28. The valve 134 may be adj usted within certain limits to vary the rich ness of the idling mixture, but as this valve regulates the suction effective to lift the fuel `to the passages 126, the valve must always be adjusted to restrict the flow of air to passages 126 enough to create a suction in such passages when the primary throttle is closed, which is great enough to lift fuel from the fuel bowl thereto. However, enough air should always be admitted by the valve 1311 to reduce the suction in passages 126 below that necessary to lift fuel thereto, when the primary throttle is slightly opened so as to render the idling fuel jets ineffective, and

prevent formation of a too rich mixture under such operating conditions.

The fuel inlets 128 are also made use of according to this invention to supply additional fuel to the mixture passages on opening movei ments of the throttle to enrich the mixture for acceleration purposes. rl`his additional. fuel is forced into the passages 126 by a pump, which, in the specific embodiment of the invention herein illustrated, is the dash pot previously described. To enable this dash pot to force fuel to the passages 126, the cylinder 100 is connected with the passage 110 by a passage 136. On opening of the throttle, the piston 102 moves downwardly forcing fuel from cylinder through passage 136 and the various passages previously described, to the passage 126, where it is mixed with air `in the same way as the idling fuel anddrawn into the primary mixture passages, as previously described. lf the pump is'effective to force more fuel intothe passages 126 than can be dra-wn from the passages 128, the surplus merely flows back into v the fuel bowl through the passages 13() and 132. The previously described check valve 114e is operative to prevent fuel forced `from the cylinder 100 passing directly into the fuel bowl through the orifice 118.

The Secondary mixing chambers to which the primary mixture is delivered under all operating conditions are of identical construction and are associated with all the outlet branches of the manifold. One of these chambers is shown herein and comprises a Venturi tube 1410, clamped between the engine block and the manifold and positioned so that the outlet of the primary mixture conduit associated therewith terminates at the point of greatest suction therein. These mixing chambers constitute no part of the present invention, but function in a manner fully set forth in the above mentioned applications.

The advantages secured by the construction above described, are several. It has already been set forth how the attempt to employ the nozzles 38 to provide fuel for idling may lead to difficulties in forming a mixture of proper proportions during other operating conditions, difculties which are entirely eliminated by the provision of the construction forming the Subj ect of the present invention. Y

Further, it is known that variation in the quantity of idling fuel is necessaryto secure proper engine operation at different temperatures and under otheroperating conditions. l/Vhere such variation is attempted by varying the calibration of the fuel jets or by use of a fuel valve, when the same nozzles are employed to supply idling fuel and also to supply fuel during normal operation, it has been found by actual experiment that a greater variation in the flow from the nozzles is ef-` By the provision of separate fuel inlets for idling independent of the main fuel inlets, the supply of fuel at idling may be regulated as desired without any effect on the mixture proportions under any other conditions of 10? engine operation.

A still further advantage secured by the present invention is the superior distribution of fuel for idling and acceleration. lhere a common fuel passage is employed to supply fuel in the form of a fuel emulsion to several separate mixing chambers, it is impossible to secure equal distribution of the fuel when it is attempted to divide the emulsion into several parts. According to this Zo invention the fuel, in liquid form, is divided into a plurality of equal parts and is then mixed with air to form the emulsion, which is drawn into the mixing chambers on idling operation and during the acceleration period,

thus insuring equal distribution of the fuel under these specific operating conditions.

In addition, the device is simple in construction, easy to manufacture, and is provided with a simple means of adjustment to control the quantity of fuel and mixture proportions in the manner desired.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that "other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows: l. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets therefor, a thr0ttle in said mixture passage, an auxiliary fuel inlet for supplying fuel to said mixture passage, a fuel passage communicating therewith, means for creating sufficient suction to lift fuel through said passage to said auxiliary inlet when the throttle is closed to supply fuel for idling, a fuel reservoir, a pump for forcing fuel through said passage on opening movements of the throttle, a passage connecting the auxiliary fuel inlet with the fuel reservoir above the fuel therein, and operating to permit return of surplus fuel to said reservoir on operation of the pump.

2. A charge forming device for internal combustion engines comprising a plurality of mixture passages, means for supplying fuel and air to each of said passages, a. plurality of auxiliary fuel inlets, each of which is adapted to supply an emulsion of fuel and air to each of said mixture passages, a common fuel passage adapted to supply fuel to all of said auxiliary inlets, means for supplying air to mix with the fuel supplied through said common fuel passage, and

means for securing equal distribution of the fuel from said common fuel passage to each of the mixture passages.

3. A charge forming device for internal combustion engines comprising a plurality of mixture passages, means for supplying fuel and air to each of said passages, a plurality of auxiliary fuel inlets, each of which is adapted to supply an emulsion of fuel and air to each of said mixture passages, a common fuel passage adapted to supply fuel to all of said auxiliary inlets, means for supplying air to mix with the fuel supplied through said common fuel passage, and means for dividing the fuel supplied through said common fuel passage into a number of parts equal to the number of mixture passages before such fuel is mixed with air, wherebv equal distribution of the fuel to each o1' the mixture passages is secured.

1l. `A charge forming device for internal combustion engines comprising a plurality of mixture passages, means for supplying fuel and air to each of said passages, a plu rality of auxiliary fuel inlets, each of which is adapted to supply an emulsion of fuel and air to each of said mixture passages, a common fuel supply passage adapted to supply fuel to all of said auxiliary fuel inlets, a plurality of passages communicating with said common fuel passage and adapted to convey fuel therefrom to said auxiliary fuel inlets, and means for supplying air to the last mentioned passages to form an emulsion of fuel and air therein.

5. A charge forming device for internal combustion engines comprising a plurality of mixture passages, means for supplying fuel and air to each of said passages, a plurality of auxiliary fuel inlets, each of which is adapted to supply an emulsion of fuel and air to each of said mixture passages, a common fuel supply passage adapted to supply fuel to all of said auxiliary fuel inlets, a plurality of passages communicating with said common fuel passage and adapted to convey fuel therefrom to said auxiliary fuel inlets, a single air inlet for supplying air to all of said last mentioned passages and means for regulating the flow of air therethrough.

In testimony whereof I hereto aiiix my signature.

VVILFORD H. TEETER. 

